The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to form pulse width modulated (PWM) power supply controllers. PWM controllers generally were used in a power supply to regulate an output voltage to a desired value. In one configuration, the power supply controllers functioned as a voltage mode controller that used the value of the output voltage to form a closed loop regulation system. Some of these voltage mode controllers also incorporated voltage feed forward that utilized the value of the input voltage to assist in regulating the output voltage. One example of such a power supply controller was the UCC35701 that was supplied by Texas Instruments, Inc. of Dallas Tex. One problem was that these prior controllers only utilized the inductor current as a current limit in order to limit the maximum value of the current supplied to the inductor. Another problem was that oscillations or overshoots in the value of the output voltage may occur in response to transient conditions of the load current or transient conditions of the input voltage that was supplied to the power supply.
Accordingly, it is desirable to have a power supply controller which more accurately regulates the value of the output voltage in response to a change in the input voltage, in response to a change in the current required by the load, or in response to noise signals on the input voltage.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.